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1a2d0914e2
To support two stage irq vector spreading, it's required to add a starting point to the spreading function. No functional change, just preparatory work for the actual two stage change. [ tglx: Renamed variables, tidied up the code and massaged changelog ] Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Cc: Laurence Oberman <loberman@redhat.com> Cc: Christoph Hellwig <hch@infradead.org> Link: https://lkml.kernel.org/r/20180308105358.1506-4-ming.lei@redhat.com
240 lines
5.9 KiB
C
240 lines
5.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2016 Thomas Gleixner.
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* Copyright (C) 2016-2017 Christoph Hellwig.
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*/
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include <linux/cpu.h>
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static void irq_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
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int cpus_per_vec)
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{
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const struct cpumask *siblmsk;
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int cpu, sibl;
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for ( ; cpus_per_vec > 0; ) {
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cpu = cpumask_first(nmsk);
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/* Should not happen, but I'm too lazy to think about it */
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if (cpu >= nr_cpu_ids)
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return;
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cpumask_clear_cpu(cpu, nmsk);
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cpumask_set_cpu(cpu, irqmsk);
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cpus_per_vec--;
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/* If the cpu has siblings, use them first */
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siblmsk = topology_sibling_cpumask(cpu);
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for (sibl = -1; cpus_per_vec > 0; ) {
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sibl = cpumask_next(sibl, siblmsk);
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if (sibl >= nr_cpu_ids)
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break;
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if (!cpumask_test_and_clear_cpu(sibl, nmsk))
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continue;
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cpumask_set_cpu(sibl, irqmsk);
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cpus_per_vec--;
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}
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}
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}
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static cpumask_var_t *alloc_node_to_cpumask(void)
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{
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cpumask_var_t *masks;
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int node;
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masks = kcalloc(nr_node_ids, sizeof(cpumask_var_t), GFP_KERNEL);
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if (!masks)
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return NULL;
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for (node = 0; node < nr_node_ids; node++) {
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if (!zalloc_cpumask_var(&masks[node], GFP_KERNEL))
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goto out_unwind;
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}
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return masks;
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out_unwind:
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while (--node >= 0)
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free_cpumask_var(masks[node]);
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kfree(masks);
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return NULL;
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}
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static void free_node_to_cpumask(cpumask_var_t *masks)
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{
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int node;
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for (node = 0; node < nr_node_ids; node++)
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free_cpumask_var(masks[node]);
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kfree(masks);
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}
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static void build_node_to_cpumask(cpumask_var_t *masks)
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{
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int cpu;
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for_each_possible_cpu(cpu)
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cpumask_set_cpu(cpu, masks[cpu_to_node(cpu)]);
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}
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static int get_nodes_in_cpumask(cpumask_var_t *node_to_cpumask,
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const struct cpumask *mask, nodemask_t *nodemsk)
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{
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int n, nodes = 0;
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/* Calculate the number of nodes in the supplied affinity mask */
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for_each_node(n) {
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if (cpumask_intersects(mask, node_to_cpumask[n])) {
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node_set(n, *nodemsk);
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nodes++;
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}
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}
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return nodes;
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}
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static int irq_build_affinity_masks(const struct irq_affinity *affd,
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int startvec, int numvecs,
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cpumask_var_t *node_to_cpumask,
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const struct cpumask *cpu_mask,
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struct cpumask *nmsk,
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struct cpumask *masks)
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{
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int n, nodes, cpus_per_vec, extra_vecs, done = 0;
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int last_affv = affd->pre_vectors + numvecs;
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int curvec = startvec;
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nodemask_t nodemsk = NODE_MASK_NONE;
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nodes = get_nodes_in_cpumask(node_to_cpumask, cpu_mask, &nodemsk);
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/*
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* If the number of nodes in the mask is greater than or equal the
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* number of vectors we just spread the vectors across the nodes.
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*/
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if (numvecs <= nodes) {
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for_each_node_mask(n, nodemsk) {
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cpumask_copy(masks + curvec, node_to_cpumask[n]);
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if (++done == numvecs)
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break;
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if (++curvec == last_affv)
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curvec = affd->pre_vectors;
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}
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goto out;
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}
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for_each_node_mask(n, nodemsk) {
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int ncpus, v, vecs_to_assign, vecs_per_node;
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/* Spread the vectors per node */
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vecs_per_node = (numvecs - (curvec - affd->pre_vectors)) / nodes;
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/* Get the cpus on this node which are in the mask */
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cpumask_and(nmsk, cpu_mask, node_to_cpumask[n]);
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/* Calculate the number of cpus per vector */
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ncpus = cpumask_weight(nmsk);
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vecs_to_assign = min(vecs_per_node, ncpus);
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/* Account for rounding errors */
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extra_vecs = ncpus - vecs_to_assign * (ncpus / vecs_to_assign);
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for (v = 0; curvec < last_affv && v < vecs_to_assign;
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curvec++, v++) {
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cpus_per_vec = ncpus / vecs_to_assign;
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/* Account for extra vectors to compensate rounding errors */
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if (extra_vecs) {
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cpus_per_vec++;
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--extra_vecs;
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}
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irq_spread_init_one(masks + curvec, nmsk, cpus_per_vec);
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}
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done += v;
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if (done >= numvecs)
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break;
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if (curvec >= last_affv)
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curvec = affd->pre_vectors;
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--nodes;
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}
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out:
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return done;
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}
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/**
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* irq_create_affinity_masks - Create affinity masks for multiqueue spreading
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* @nvecs: The total number of vectors
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* @affd: Description of the affinity requirements
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*
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* Returns the masks pointer or NULL if allocation failed.
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*/
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struct cpumask *
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irq_create_affinity_masks(int nvecs, const struct irq_affinity *affd)
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{
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int curvec, affvecs = nvecs - affd->pre_vectors - affd->post_vectors;
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cpumask_var_t nmsk, *node_to_cpumask;
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struct cpumask *masks = NULL;
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/*
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* If there aren't any vectors left after applying the pre/post
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* vectors don't bother with assigning affinity.
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*/
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if (nvecs == affd->pre_vectors + affd->post_vectors)
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return NULL;
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if (!zalloc_cpumask_var(&nmsk, GFP_KERNEL))
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return NULL;
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node_to_cpumask = alloc_node_to_cpumask();
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if (!node_to_cpumask)
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goto outcpumsk;
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masks = kcalloc(nvecs, sizeof(*masks), GFP_KERNEL);
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if (!masks)
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goto outnodemsk;
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/* Fill out vectors at the beginning that don't need affinity */
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for (curvec = 0; curvec < affd->pre_vectors; curvec++)
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cpumask_copy(masks + curvec, irq_default_affinity);
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/* Stabilize the cpumasks */
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get_online_cpus();
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build_node_to_cpumask(node_to_cpumask);
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curvec += irq_build_affinity_masks(affd, curvec, affvecs,
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node_to_cpumask, cpu_possible_mask,
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nmsk, masks);
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put_online_cpus();
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/* Fill out vectors at the end that don't need affinity */
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for (; curvec < nvecs; curvec++)
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cpumask_copy(masks + curvec, irq_default_affinity);
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outnodemsk:
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free_node_to_cpumask(node_to_cpumask);
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outcpumsk:
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free_cpumask_var(nmsk);
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return masks;
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}
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/**
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* irq_calc_affinity_vectors - Calculate the optimal number of vectors
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* @minvec: The minimum number of vectors available
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* @maxvec: The maximum number of vectors available
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* @affd: Description of the affinity requirements
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*/
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int irq_calc_affinity_vectors(int minvec, int maxvec, const struct irq_affinity *affd)
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{
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int resv = affd->pre_vectors + affd->post_vectors;
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int vecs = maxvec - resv;
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int ret;
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if (resv > minvec)
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return 0;
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get_online_cpus();
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ret = min_t(int, cpumask_weight(cpu_possible_mask), vecs) + resv;
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put_online_cpus();
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return ret;
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}
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